1. Department of pulmonology R4 Ja Won Koo
Disease Review Dysfunction of the Diaphragm N Engl J Med 2012;366:
Department of pulmonology
R4 Ja Won Koo

2. Diaphragm Dome-shaped Separates the thoracic and abdominal cavities
Innervated by the phrenic nerves from C3~C5
Fatigue-resistant slow-twitch type I and fast-twitch type IIa myofibers

3. Clinical feature
Unexplained dyspnea  rule out diaphragmatic dysfunction
Partial loss of the ability to generate pressure (weakness) to complete loss of diaphragmatic function (paralysis).
involve either one or both hemidiaphragms
Etiology : metabolic or inflammatory disorders, after trauma or surgery, during mechanical ventilation, and with mediastinal masses, myopathies, neuropathies, or diseases that cause lung hyperinflation.

4. Unilateral diaphragmatic paralysis : asymptomatic, dyspnea on exertion, limited ability to exercise, supine position dyspnea
Bilateral diaphragmatic paralysis
unexplained dyspnea or recurrent respiratory failure
Dyspnea : rest, supine, exertion, in water above their waist
sleep fragmentation and hypoventilation during sleep
fatigue, hypersomnia, depression, morning headaches, and frequent nocturnal awakenings
Subsegmental atelectasis and infections of the lower respiratory tract

5. Physical examination
Tachypnea and use of accessory muscles - contraction of the sternocleidomastoid muscles
Abdominal paradox : maximum transdiaphragmatic pressure <30 cm of water

6. Natural history
Cause and Rate of progression of the underlying disease
Neuromuscular : progressive
Traumatic or infectious : spontaneous
Phrenic nerve - Regeneration time : 3years
Neuralgic amyotrophy - typically in 1 to 1.5 years
Cardiac surgery : shorter,
Spinal injury : poor prognosis
Hypoventilation :
Age-related changes
Respiratory drive
Respiratory-muscle strength
Chest-wall compliance

7. Causes
Classified by the level of the impairment

8. Spinal cord injuries
C1, C2 : Diaphragmatic paralysis
C3~C5 : Partially preserved (C3 : 40% MV, C5 : 15% MV)
Damage to the phrenic nerve :
Iatrogenic injury during surgery (transection, stretching, crushing, hypothermia)
compression caused by bronchogenic or mediastinal tumors
Trauma
infections (Herpes zoster and Lyme disease)
Inflammatory disorders
Guillain–Barré syndrome : 25% need Mechanical Ventilation

9. Disordered synaptic transmission at the neuromuscular junction
myasthenia gravis
Botulinum toxins
Aminoglycosides
Critical illness polyneuropathy and myopathy
Sepsis, multiorgan failure, and Hyperglycemia
Disuse atrophy of the diaphragm – mechanical ventilation, paralyzing agents
Undernutrition and metabolic abnormalities
COPD (lung hyperinflation) - shortening the diaphragm, lesser extend  mechanical disadventage

10. Diagnosis Chest radiographs :
Elevated hemidiaphragms, basal subsegmental atelectasis
Unilateral dysfunction : sensitivity : 90%, specificity : 44%
Bilateral elevation : poor inspiratory effort, low lung volumes
Fluoroscopy of the diaphragm
Sniff test : assessing the motion of the diaphragm during a short, sharp inspiratory effort
Normal : Descent of the diaphragm
Unilateral diaphragmatic paralysis : paradoxical (cephalad) movement of the paralyzed hemidiaphragm

11. Pulmonary-function tests
TLC : Unilateral 70~79% of pred, Bilateral 30~50% of pred
Upright and supine Vital Capacity
Supine position VC decrease : Unilateral 10~30%, Bilateral 30~50%
FRC and RV : no decrease in unilateral
Maximal static inspiratory pressure and sniff nasal inspiratory pressure : Unilateral 60% of pred, bilateral 30% of pred
Maximal expiratory pressure : spare expiratory muscle

12. Transdiaphragmatic pressure [Pdi]
Difference of Gastric and esophageal pressure
sniff Pdi : maximal sniff maneuvers
Pdimax : maximal inspiratory efforts
twitch Pdi : transcutaneous electrical or magnetic stimulation of the phrenic nerve – standard for diagnosis of bilateral paralysis
Normal range :
sniff Pdi or Pdi max ≥ 80 cm of water(men), ≥ 70 cm of water (women)
twitch Pdi ≥ 10 cm of water with unilateral phrenic-nerve stimulation
≥ 20 cm of water with bilateral phrenic-nerve stimulation

13. Ultrasonography
Zone of apposition
Normal : Thickening of the diaphragm during inspiration
Diagnosis and monitoring
Central tendon of the diaphragm, not the muscular component
Electromyography of the diaphragm
Queit breathing or stimulation of the phrenic nerve
Useful in distinguishing between neuropathic and myopathic
Limitation : technical issue

15. Treatment Cause, Nocturnal hypoventilation Treatable cause
myopathies related to metabolic disturbances,
Myopathies due to parasitic infection,
Idiopathic diaphragmatic paralysis
paralysis due to neuralgic amyotrophy
Persists or progresses : ventilatory support
Ix. for initiating nocturnal noninvasive ventilation
pCO2 ≥ 45mmHg in day time
O2 saturation ≤ 88%, 5min at night
Maximal static inspiratory pressure < 60 cm of water or FVC < 50% of pred in progressive neuromuscular disease

16. Plication of the diaphragm - unilateral diaphragmatic paralysis
increases of up to 20 % in VC, FEV1, and TLC with improvement in dyspnea
Eur J Cardiothorac Surg Sep;32(3): Epub 2007 Jul 19

17. high cervical cord quadriplegia, central hypoventilation
Phrenic pacing
potential to provide full ventilatory support in bilateral paralysis, intact phrenic nerve
high cervical cord quadriplegia, central hypoventilation
laparoscopic mapping of motor points and intramuscular stimulation of the diaphragm